Surface features mapping

ABSTRACT

Provided herein is an apparatus, including a photon emitting means for emitting photons onto a surface of an article, a photon detecting means for detecting photons scattered from features in the surface of the article; and a mapping means for mapping the features in the surface of the article, wherein the apparatus is configured to process more than one article every  100  seconds.

CROSS REFERENCE

This application claims the benefit of U.S. Provisional PatentApplication No. 61644998, filed May 9, 2012.

BACKGROUND

An article fabricated on a production line may be inspected for certainfeatures, including defects that might degrade the performance of thearticle or a system comprising the article. For example, a hard disk fora hard disk drive may be fabricated on a production line and inspectedfor certain surface features, including surface and subsurface defectsthat might degrade the performance of the disk or the hard disk drive.Accordingly, apparatuses and methods operable to inspect articles forfeatures such as defects are merited.

SUMMARY

Provided herein is an apparatus, including a photon emitting means foremitting photons onto a surface of an article, a photon detecting meansfor detecting photons scattered from features in the surface of thearticle; and a mapping means for mapping the features in the surface ofthe article, wherein the apparatus is configured to process more thanone article every 100 seconds.

These and other features and aspects of the invention may be betterunderstood with reference to the following drawings, description, andappended claims.

DRAWINGS

FIG. 1 provides a schematic illustrating detection of surface featuresof articles in accordance with an embodiment.

FIG. 2 provides a schematic illustrating photon scattering from asurface feature of an article in accordance with an embodiment.

FIG. 3 provides a schematic illustrating photons scattering from asurface feature of an article, through an optical component, and onto aphoton detector array in accordance with an embodiment.

FIG. 4 provides an image of a map of surface features of an article inaccordance with an embodiment.

FIG. 5 provides a close-up image of the map of surface features providedin FIG. 4.

FIG. 6A (top) provides a close-up image of a surface feature from themap provided in FIG. 5, and FIG. 6A (bottom) provides photon scatteringintensity distribution of the surface feature.

FIG. 6B (top) provides a pixel-interpolated image of the surface featurefrom FIG. 6A, and FIG. 6B (bottom) provides a pixel-interpolated photonscattering intensity distribution of the surface feature.

DESCRIPTION

Before embodiments of the invention are described in greater detail, itshould be understood by persons having ordinary skill in the art towhich the invention pertains that the invention is not limited to theparticular embodiments described and/or illustrated herein, as elementsin such embodiments may vary. It should likewise be understood that aparticular embodiment described and/or illustrated herein has elementswhich may be readily separated from the particular embodiment andoptionally combined with any of several other embodiments or substitutedfor elements in any of several other embodiments described herein.

It should also be understood by persons having ordinary skill in the artto which the invention pertains that the terminology used herein is forthe purpose of describing particular embodiments of the invention, andthe terminology is not intended to be limiting. Unless indicatedotherwise, ordinal numbers (e.g., first, second, third, etc.) are usedto distinguish or identify different elements or steps in a group ofelements or steps, and do not supply a serial or numerical limitation onthe elements or steps of the claimed invention or particular embodimentsof the invention. For example, “first,” “second,” and “third” elementsor steps need not necessarily appear in that order, and the claimedinvention, or particular embodiments of the invention, need notnecessarily be limited to three elements or steps. It should also beunderstood that, unless indicated otherwise, any labels such as “left,”“right,” “front,” “back,” “top,” “bottom,” “forward,” “reverse,”“clockwise,” “counter clockwise,” “up,” “down,” or other similar termssuch as “upper,” “lower,” “aft,” “fore,” “vertical,” “horizontal,”“proximal,” “distal,” and the like are used for convenience and are notintended to imply, for example, any particular fixed location,orientation, or direction. Instead, such labels are used to reflect, forexample, relative location, orientation, or directions. It should alsobe understood that the singular forms of “a,” “an,” and “the” includeplural references unless the context clearly dictates otherwise.

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as commonly understood by persons of ordinaryskill in the art to which the invention pertains.

An article fabricated on a production line may be inspected for certainfeatures, including defects that might degrade the performance of thearticle or a system comprising the article. For example, a hard disk fora hard disk drive may be fabricated on a production line and inspectedfor certain surface features, including surface and subsurface defectsthat might degrade the performance of the disk or the hard disk drive.Provided herein are apparatuses and methods for inspecting articles todetect and/or map certain surface features such as surface and/orsubsurface defects. Embodiments of the invention will now be describedin greater detail.

With respect to articles that may be inspected with apparatuses andmethods herein, such articles include any article of manufacture or aworkpiece thereof in any stage of manufacture having one or moreoptically smooth surfaces, examples of which include, but are notlimited to, semiconductor wafers, magnetic recording media (e.g., harddisks for hard disk drives), and workpieces thereof in any stage ofmanufacture. Such articles may be inspected for certain features,including surface and/or subsurface defects that might degrade theperformance of the article, which surface and/or subsurface defectsinclude particle and stain contamination, as well as defects includingscratches and voids. With respect to particle contamination, forexample, particles trapped on a surface of an intermediate hard disk(i.e., workpiece) for a hard disk drive may damage subsequentlysputtered films. Particle contamination may also contaminate a finishedsurface of a hard disk drive, leading to scratch formation, debrisgeneration, and corruption of the spacing between the hard disk and theread-write head. As such, it is important to inspect articles withapparatus and methods herein to correct manufacturing trends leading tosurface and/or subsurface defects and to increase product quality.

FIG. 1 provides a schematic for detection and/or mapping of surfacefeatures of articles, illustrating an apparatus 100 comprising a photonemitter 110, an optical setup 120, a photon detector array 130, and amapping means 140, as well as an article 150 and a surface features map160 of a surface of the article 150 in accordance with an embodiment;however, the articles and apparatuses of the invention, as well asmethods of the invention, are not limited to the embodiments in FIG. 1,as additional embodiments of the invention may be realized by thefeatures described in more detail herein.

An apparatus for detection and/or mapping of surface features ofarticles may comprise a single photon emitter (e.g., see photon emitter110 of FIG. 1) or a plurality of photon emitters, which may be used toemit photons onto a surface of an article, such as the entire surface ofthe article or some predetermined portion of the surface of the article(e.g., for gradational rotation of the article for piecewise inspection,if desired). In some embodiments, for example, the plurality of photonemitters may comprise at least 2, 3, 4, 5, 6, 7, 8, 9, or 10 photonemitters. In some embodiments, for example, the plurality of photonemitters may comprise no more than 10, 9, 8, 7, 6, 5, 4, 3, or 2 photonemitters. Combinations of the foregoing may also be used to describe theplurality of photon emitters. In some embodiments, for example, theplurality of photon emitters may comprise at least 2 photon emitters andno more than 10 photon emitters (e.g., between 2 and 10 photonemitters), such as at least 2 photon emitters and no more than 5 photonemitters (e.g., between 2 and 5 photon emitters). Further with respectto the plurality of photon emitters, each photon emitter of theplurality of photon emitters may be the same or different, or somecombination thereof (e.g., at least 2 of the same photon emitter, withthe remainder of photon emitters being different; at least 3 of the samephoton emitter, with the remainder of photon emitters being different;etc.).

Whether the apparatus for detection and/or mapping of surface featuresof articles comprises a single photon emitter or a plurality of photonemitters, each photon emitter may emit photons onto a surface of anarticle at an optimized distance and/or optimized angle for one or moretypes of features, which types of features are described in more detailherein. The angle optimized for one or more types of features may beequal to the angle of incidence, which is the angle between a raycomprising the emitted photons incident on the surface of the articleand the normal (i.e., a line perpendicular to the surface of thearticle) at the point at which the ray is incident. FIG. 2 provides anumber of rays comprising emitted photons incident on a surface 152 ofan article 150 that form an angle of incidence with the normal to thesurface. A photon emitter may be optimized to emit photons at an angleof incidence ranging from 0° to 90°, wherein an angle of incidence of 0°represents the photon emitter emitting photons onto the surface of thearticle from a side of the article, and wherein an angle of incidence of90° represents the photon emitter emitting photons onto the surface ofthe article from directly above the article. In some embodiments, forexample, a photon emitter may emit photons onto a surface of an articlesuch that the angle of incidence is at least 0°, 5°, 10°, 15°, 20°, 25°,30°, 35°, 40°, 45°, 50°, 55°, 60°, 65°, 70°, 75°, 80°, 85°, or 90° . Insome embodiments, for example, a photon emitter may emit photons onto asurface of an article such that the angle of incidence is no more than90°, 85°, 80°, 75°, 70°, 65°, 60°, 55°, 50°, 45°, 40°, 35°, 30°, 25°,20°, 15°, 10°, or 5°. Combinations of the foregoing may also be used todescribe the angle of incidence at which a photon emitter may emitphotons onto a surface of an article. In some embodiments, for example,a photon emitter may emit photons onto a surface of an article such thatthe angle of incidence is at least a 0° and no more than 90° (i.e.,between 0° and 90°), such as least 0° and no more than 45° (i.e.,between 0° and 45°), including at least 45° and no more than 90° (i.e.,between 45° and 90°).

A photon emitter, optionally in combination with one or more additionalphoton emitters, and further optionally in combination with one or moreadditional photon emitters of the same type, may emit photons onto asurface of an article, such as the entire surface or some predeterminedportion of the surface (e.g., for gradational rotation of the articlefor piecewise inspection, if desired). The photon emitter, optionally incombination with the one or more additional photon emitters, and furtheroptionally in combination with the one or more additional photonemitters of the same type, may further emit photons onto the entiresurface of the article or some predetermined portion of the surface suchthat the entire surface or the predetermined portion of the surface isuniformly or homogenously illuminated. Uniformly illuminating the entiresurface of the article or some predetermined portion of the surfaceincludes, but is not limited to, subjecting the entire surface of thearticle or some predetermined portion of the surface of the article tothe same or about the same photon energy per unit time (e.g., photonpower or photon flux) and/or photon power per unit area (e.g., photonflux density). In radiometric terms, uniformly illuminating includes,but is not limited to, subjecting the entire surface of the article orsome predetermined portion of the surface of the article to the same orabout the same radiant energy per unit time (e.g., radiant power orradiant flux) and/or radiant power per unit area (e.g., irradiance orradiant flux density).

With the appreciation that photons are the elementary particles ofelectromagnetic radiation or light, a photon emitter or light source mayprovide light comprising a relatively wide range of wavelengths (e.g.,ultraviolet-visible, visible, infrared, etc.), a relatively narrow rangeof wavelengths (e.g., a subdivision of ultraviolet such as UVA, UVB,UVC, etc.; a subdivision of visible such as red, green, blue, etc.; asubdivision of infrared such as near infrared, mid-infrared; etc.), or aparticular wavelength (e.g., monochromatic); light comprising arelatively wide range of frequencies (e.g., ultraviolet-visible,visible, infrared, etc.), a relatively narrow range of frequencies(e.g., a subdivision of ultraviolet such as UVA, UVB, UVC, etc.; asubdivision of visible such as red, green, blue, etc.; a subdivision ofinfrared such as near infrared, mid-infrared; etc.), or a particularfrequency (e.g., monochromatic); polarized (e.g., linear polarization,circular polarization, etc.) light, partially polarized light, ornonpolarized light; and/or light with different degrees of temporaland/or spatial coherence ranging from coherent light (e.g., laser) tononcoherent light. As discussed herein, a photon emitter or light sourcemay be used in conjunction with one or more optical components of anoptical setup to provide light having any of the foregoing qualities.

In view of the foregoing, a photon emitter or light source may comprisea lamp such as a flash lamp, including a high-speed flash lamp,configured to minimize vibration while detecting photons scattered fromfeatures in a surface of an article with a photon detector array. Insome embodiments, for example, a photon emitter or light source maycomprise a high-speed Xe flash lamp such as a 500 W Xe flash lamp tominimize vibration while detecting photons scattered from features in asurface of an article with a photon detector array.

Also in view of the foregoing, a photon emitter or light source maycomprise a collimated light source such as a laser, including acombination of lasers, configured to emit photons onto a surface of anarticle at one or more angles. In some embodiments, for example, acombination of lasers may be provided to a laser beam shaper such thatthe combination of lasers emits photons onto a surface of an article atone angle. In some embodiments, for example, a combination of lasers maybe provided to a laser beam shaper such that the combination of lasersemits photons onto a surface of an article at multiple angles. In someembodiments, for example, at least 2, 4, 6, 8, 10, 12, 14, 16, 18, 20,22, 24, 26, 28, or 30 lasers (or more) may be provided to a laser beamshaper such that the combination of lasers emits photons onto a surfaceof an article at one or more angles. In some embodiments, for example,no more than 30, 28, 26, 24, 22, 20, 18, 16, 14, 12, 10, 8, 6, 4, or 2lasers may be provided to a laser beam shaper such that the combinationof lasers emits photons onto a surface of an article at one or moreangles. Combinations of the foregoing may also be used to describecombinations of lasers provided to a laser beam shaper. In someembodiments, for example, at least 2 lasers and no more than 30 lasers(e.g., between 2 and 30 lasers), such as at least 10 lasers and no morethan 30 lasers (e.g., between 10 and 30 lasers), including at least 20lasers and no more than 30 lasers (e.g., between 20 and 30 lasers), andfurther including at least 24 lasers and no more than 28 lasers (e.g.,between 24 and 28 lasers) may be provided to a laser beam shaper suchthat the combination of lasers emits photons onto a surface of anarticle of an article at one or more angles.

Further in view of the foregoing, a photon emitter or light source maycomprise a two-dimensional light source such as a combination of pointlight sources, including a linear combination, an arcuate combination,etc. of point light sources configured to emit photons onto a surface ofan article. In some embodiments, for example, a two-dimensional lightsource may comprise a combination of at least 10, 20, 40, 60, 80, 100,110, 120, 140, 160, 180, or 200 (or more) point light sources. In someembodiments, for example, a two-dimensional light source may comprise acombination of no more than 200, 180, 160, 140, 120, 100, 80, 60, 40,20, or 10 point light sources. Combinations of the foregoing may also beused to describe two-dimensional light sources comprising combinationsof point light sources. In some embodiments, for example, atwo-dimensional light source may comprise a combination of at least 10and no more than 200 (e.g., between 10 and 200) point light sources,such as at least 40 and no more than 160 (e.g., between 40 and 160)point light sources, including at least 60 and no more than 140 (e.g.,between 60 and 140) point light sources, and further including at least80 and no more than 120 (e.g., between 80 and 120) point light sources.Such point light sources may be linearly combined to form atwo-dimensional light source such as a strip light. Such point lightsources may be arcuately combined to form a two-dimensional light sourcesuch as a ring light. In some embodiments, for example, a photon emitteror light source may comprise a two-dimensional light source comprisingat least 60 point light sources, such as a ring light comprising atleast 60 point light sources, including a ring light comprising at least60 light-emitting diodes (“LEDs”), and further including a ring lightcomprising at least 100 LEDs. A two-dimensional light source comprisingLEDs may comprise white LEDs, wherein each LED has a power of at least10 mW. An LED-based ring light may enhance features such as scratches(e.g., circumferential scratches) and/or voids in surfaces of articles,especially when the LED-based ring light is configured to emit photonsonto the surfaces of the articles with lower angles (e.g., angle ofincidence equal to or less than) 45°.

An apparatus for detection and/or mapping of surface features ofarticles may further comprise an optical setup (e.g., see optical setup120 of FIG. 1), which optical setup may manipulate photons emitted fromone or more photon emitters and/or photons scattered from surfacefeatures of articles. With the appreciation that photons are theelementary particles of electromagnetic radiation or light, the opticalsetup may manipulate light emitted from one or more photon emittersand/or light scattered from surface features of articles. The opticalsetup up may comprise any of a number of optical components placed inthe optical path before an article such that the optical components maybe used to manipulate photons/light emitted from one or more photonemitters before uniformly or homogenously illuminating the entiresurface or the predetermined portion of the surface of the article. Theoptical setup up may comprise any of a number of optical componentsplaced in the optical path after an article such that the opticalcomponents may be used to manipulate photons/light scattered fromfeatures in a surface of the article. The forgoing optical componentsmay include, but are not limited to, optical components such as lenses,mirrors, and filters. With respect to optical components such asfilters, such filters may include, for example, wave filters andpolarization filters. Wave filters may be used in conjunction withphoton emitters described herein to provide light comprising arelatively wide range of wavelengths/frequencies, a relatively narrowrange of wavelengths/frequencies, or a particular wavelength/frequency.Polarization filters may be used in conjunction with photon emittersdescribed herein to provide light of a desired polarization includingpolarized light, partially polarized light, or nonpolarized light.

An optical setup for an apparatus for detection and/or mapping ofsurface features of articles may comprise a single lens or a pluralityof lenses, including, but not limited to, a combination of a lenscoupled to a photon detector array (e.g., photon detector array 130 ofFIG. 1) for collecting and detecting photons scattered from features ina surface of an article. The lens coupled to the photon detector arraymay be an objective lens, such as a telecentric lens, including anobject-space telecentric lens (i.e., entrance pupil at infinity), animage-space telecentric lens (i.e., exit pupil at infinity), or a doubletelecentric lens (i.e., both pupils at infinity). Coupling a telecentriclens to a photon detector array reduces errors with respect to themapped position of surface features of articles, reduces distortion ofsurface features of articles, and/or enables quantitative analysis ofphotons scattered from surface features of articles, which quantitativeanalysis includes integration of photon scattering intensitydistribution for size determination of surface features of articles.

To detect photons scattered from surface features of articles, anapparatus for detection and/or mapping of surface features of articlesmay further comprise a single photon detector array (e.g., see photondetector array 130 of FIG. 1) comprising a plurality of photon detectorsor a plurality of photon detector arrays, each comprising a plurality ofphoton detectors. In some embodiments, for example, the plurality ofphoton detector arrays may comprise at least 2, 3, 4, 5, 6, 7, 8, 9, or10 photon detector arrays. In some embodiments, for example, theplurality of photon detector arrays may comprise no more than 10, 9, 8,7, 6, 5, 4, 3, or 2 photon detector arrays. Combinations of theforegoing may also be used to describe the plurality of photon detectorarrays. In some embodiments, for example, the plurality of photondetector arrays may comprise at least 2 photon detector arrays and nomore than 10 photon detector arrays (e.g., between 2 and 10 photondetector arrays), such as at least 2 photon detector arrays and no morethan 5 photon detector arrays (e.g., between 2 and 5 photon detectorarrays). Further with respect to the plurality of photon detectorarrays, each photon detector array of the plurality of photon detectorarrays may be the same or different, or some combination thereof (e.g.,at least 2 of the same photon detector array, with the remainder ofphoton detector arrays being different; at least 3 of the same photondetector array, with the remainder of photon detector arrays beingdifferent; etc.).

Whether the apparatus comprises a single photon detector array or aplurality of photon detector arrays, each photon detector array may beoriented to detect photons scattered from surface features of an articleat an optimized distance and/or an optimized angle for a maximumacceptance of scattered light and/or one or more types of features,which types of features are described in more detail herein. Likewise, aphoton detector array and lens (e.g., telecentric lens) combination maybe oriented to collect and detect photons scattered from surfacefeatures of an article at an optimized distance and/or an optimizedangle for a maximum acceptance of scattered light and/or one or moretypes of features. Such an optimized angle may be the angle between aray comprising the center line axis of the photon detector array and/orthe lens extended to the surface of the article and the normal (i.e., aline perpendicular to the surface of the article) at the point at whichthe ray is extended. The optimized angle may be equal to or otherwiseinclude a scatter angle for one or more types of features, and thescatter angle may be a different angle than the angle of reflection,which angle of reflection is equal to the angle of incidence asdescribed herein. FIG. 2 provides a number of rays comprising scatteredphotons from a feature 154 on a surface 152 of an article 150 that formvarious scatter angles, as well as a number of rays comprising reflectedphotons that form an angle of reflection with the normal to the surface.A photon detector array or photon detector array and lens combinationmay be oriented at an optimized angle ranging from 0° to 90°, wherein anoptimized angle of 0° represents orientation of the photon detectorarray or the photon detector array and lens combination at a side of thearticle, and wherein an optimized angle of 90° represents orientation ofthe photon detector array or photon detector array and lens combinationdirectly above the article. In some embodiments, for example, a photondetector array or photon detector array and lens combination may beoriented at an optimized angle of at least 0°, 5°, 10°, 15°, 20°, 25°,30°, 35°, 40°, 45°, 50°, 55°, 60°, 65°, 70°, 75°, 80°, 85°, or 90° . Insome embodiments, for example, a photon detector array or photondetector array and lens combination may be oriented at an optimizedangle of no more than 90°, 85°, 80°, 75°, 70°, 65°, 60°, 55°, 50°, 45°,40°, 35°, 30°, 25°, 20°, 15°, 10°, or 5°. Combinations of the foregoingmay also be used to describe the optimized angle at which the photondetector array or photon detector array and lens combination may beoriented. In some embodiments, for example, a photon detector array orphoton detector array and lens combination may be oriented at anoptimized angle of at least a 0° and no more than a 90° (i.e., between0° and 90°), such as least 0° and no more than 45° (i.e., between 0° and45°), including at least 45° and no more than 90° (i.e., between 45° and90°).

A photon detector array, optionally in combination with a lens (e.g.,telecentric lens), and further optionally in combination with one ormore additional photon detector arrays or photon-detector-array-and-lenscombinations, and even further optionally in combination with one ormore additional photon detector arrays or photon-detector-array-and-lenscombinations of the same type, may detect photons scattered fromfeatures in a surface of an article, such as the entire surface of thearticle or some predetermined portion of the surface of the article. Thephoton detector array, optionally in combination with a lens (e.g.,telecentric lens), and further optionally in combination with one ormore additional photon detector arrays or photon-detector-array-and-lenscombinations, and even further optionally in combination with one ormore additional photon detector arrays or photon-detector-array-and-lenscombinations of the same type, may detect photons scattered fromfeatures in a surface of an article, such as the entire surface of thearticle or some predetermined portion of the surface of the article,while oriented at a distance and/or an angle optimized for a maximumacceptance of scattered light and/or one or more types of features. Asprovided herein, the angle optimized for one or more types of featuresmay be equal to or otherwise include a scatter angle for one or moretypes of features.

With the appreciation that photons are the elementary particles ofelectromagnetic radiation or light, a photon detector array or lightdetector array may detect light comprising a relatively wide range ofwavelengths (e.g., ultraviolet-visible, visible, infrared, etc.), arelatively narrow range of wavelengths (e.g., a subdivision ofultraviolet such as UVA, UVB, UVC, etc.; a subdivision of visible suchas red, green, blue, etc.; a subdivision of infrared such as nearinfrared, mid-infrared; etc.), or a particular wavelength (e.g.,monochromatic); light comprising a relatively wide range of frequencies(e.g., ultraviolet-visible, visible, infrared, etc.), a relativelynarrow range of frequencies (e.g., a subdivision of ultraviolet such asUVA, UVB, UVC, etc.; a subdivision of visible such as red, green, blue,etc.; a subdivision of infrared such as near infrared, mid-infrared;etc.), or a particular frequency (e.g., monochromatic); polarized (e.g.,linear polarization, circular polarization, etc.) light, partiallypolarized light, or nonpolarized light; and/or light with differentdegrees of temporal and/or spatial coherence ranging from coherent light(e.g., laser) to noncoherent light. As discussed herein, a photondetector array or light detector array may be used in conjunction withone or more optical components of an optical setup to detect lighthaving any of the foregoing qualities.

A photon detector array may comprise a plurality of pixel sensors, whichpixel sensors, in turn, may each comprise a photon detector (e.g., aphotodiode) coupled to a circuit comprising a transistor configured foramplification. Features of a photon detector array comprising such pixelsensors include, but are not limited to, low temperature operation(e.g., down to −40° C.), low electron noise (e.g., 2-10 e⁻RMS; 1 e⁻RMS;<1 e⁻RMS; etc.), wide dynamic range (e.g., 30,000:1, 8,500:1; 3,000:1;etc.), and/or decreased photon/light collection time. A photon detectorarray may comprise a large number of pixel sensors (e.g., ≧1,000,000 or1 M pixel sensors) arranged in rows and columns of a two-dimensionalarray, wherein each pixel sensor comprises a photon detector coupled toan amplifier. In some embodiments, for example, a photon detector arraymay comprise at least 1 M, 2 M, 3 M, 4 M, 5 M, 6 M, 7 M, 8 M, 9 M, 10 M,or more, pixel sensors arranged in rows and columns of a two-dimensionalarray. In some embodiments, for example, a photon detector array maycomprise no more than 10 M, 9 M, 8 M, 7 M, 6 M, 5 M, 4 M, 3 M, 2 M, 1 M,pixel sensors arranged in rows and columns of a two-dimensional array.Combinations of the foregoing may also be used to describe the number ofpixel sensors in a photon detector array. In some embodiments, forexample, a photon detector array may comprise at least 1 M and no morethan 10 M (e.g., between 1 M and 10 M) pixel sensors arranged in rowsand columns of a two-dimensional array, such as at least 1 M and no morethan 8 M (e.g., between 1 M and 8 M) pixel sensors, including at least 1M and no more than 6 M (e.g., between 1 M and 8 M) pixel sensors,further including at least 2 M and no more than 6 M (e.g., between 1 Mand 8 M) pixel sensors, and even further including at least 2 M and nomore than 5 M (e.g., between 2 M and 5 M) pixel sensors.

Due to surface reflections of surface features in articles and/or smallangle scattering (e.g., 47 scattering), surface features may appear muchlarger in size enabling pixel sensors larger the than surface featuresto be used. In some embodiments, for example, a photon detector arraymay comprise micrometer-sized (i.e., admits of μm units as measured)pixel sensors at least 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9μm, or 10 μm in their smallest dimension. In some embodiments, forexample, a photon detector array may comprise micrometer-sized pixelsensors no more than 10 μm, 9 μm, 8 μm, 7 μm, 6 μm, 5 μm, 4 μm, 3 μm, 2μm, or 1 μm in their smallest dimension. Combinations of the foregoingmay also be used to describe dimensions of micrometer-sized pixelsensors in photon detector arrays. In some embodiments, for example, aphoton detector array may comprise micrometer-sized pixel sensors atleast 1 μm and no more than 10 μm (e.g., between 1 μm and 10 μm) intheir smallest dimension, such as at least 1 μm and no more than 7 μm(e.g., between 1 μm and 7 μm), including at least 4 μm and no more than10 μm (e.g., between 4 μm and 10 μm), and further including at least 4μm and no more than 7 μm (e.g., between 4 μm and 7 μm). Suchmicrometer-sized pixel sensors may be used in the apparatus to detectand/or map surface features of articles that are more than 100 timessmaller than the micrometer-sized pixel sensors.

In view of the foregoing, the single photon detector array or theplurality of photon detector arrays may each comprise a complementarymetal-oxide semiconductor (“C MOS”) or a scientific complementarymetal-oxide semiconductor (“sC MOS”), each of which may optionally bepart of C MOS camera or a sC MOS camera, respectively.

FIG. 3 provides a schematic for detection of surface features in anarticle, illustrating a close-up, cross-sectional view of an apparatuscomprising an optical setup and a photon detector array. As shown,article 150 comprises a surface 152 and at least surface feature 154.Photons emitted from a single photon emitter or a plurality of photonemitters may be scattered by the surface feature 154 and collected anddetected by a combination comprising an optical setup 120 coupled to aphoton detector array 130, which combination may be place at anoptimized distance and/or an optimized angle for a maximum acceptance ofscattered photons and/or one or more types of features. The opticalsetup 120, which may comprise a telecentric lens, may collect and focusthe photons scattered from the surface feature 154 onto one or morepixel sensors 132 of photon detector array 130, which one or more pixelsensors each comprises a photon detector coupled to an amplifier. Theone or more pixel sensors 132, each of which corresponds to a pixel in amap of an article's surface features, may provide one or more signals tothe mapping means for mapping the surface feature 154 as shown, forexample, in FIG. 6A, which is a close-up image of the map of surfacefeatures provided in FIG. 5, which, in turn, is a close-up image of themap of surface features provided in FIG. 4. The mapping means maysubsequently use pixel interpolation for further mapping the surfacefeature 154 as shown in FIG. 6B.

An apparatus for detection and/or mapping of surface features ofarticles may further comprise one or more computers or equivalentdevices (e.g., devices that include primary and/or secondary memory andone or more processing elements operable to carry out arithmetic andlogical operations) loaded with appropriate instructions operable to,but not limited to, convey each article to the apparatus for inspection;position each article for inspection, optionally including gradationalrotation of the article for piecewise inspection; hold each article forinspection; insert optical components into the optical setup; removeoptical components from the optical setup; position and/or otherwiseadjust optical components for inspection; move each photon emitter intoposition for inspection, wherein the position for inspection may includean optimized photon emitter-article distance and/or angle (e.g., angleof incidence); switch each photon emitter on and off, or otherwisebetween modes for emitting photons and not emitting photons; move eachphoton detector array into position for inspection, wherein the positionfor inspection may include an optimized photon detector array-articledistance and/or angle (e.g., scatter angle); switch each photon detectorarray on and off, or otherwise between modes for detecting photons andnot detecting photons; process photon detector array signals, optionallyincluding pixel interpolation for better accuracy (e.g., 10× better thanpixel size) with respect to the mapped position of surface features; mapsurface features of articles from photon detector array signals orprocessed photon detector array signals; characterize surface featuresof articles with respect to type (e.g., particle, stains, scratches,voids, etc.) and/or size (e.g., volume from integration of photonscattering intensity distribution); catalog surface features ofarticles; and determine trends with respect to surface features ofarticles.

The apparatus comprising the one or more computers or equivalent devicesmay be operable to detect and/or map surface features of articles thatare nanometer-sized (i.e., admits of nm units as measured) or smaller intheir smallest dimension (e.g., length, width, height, or depth,depending on the surface feature); however, the apparatus is not limitedto mapping surface features of articles that are nanometer-sized orsmaller, as the apparatus may be operable to map surface features ofarticles that are micrometer-sized (i.e., admits of μm units asmeasured) or larger. In some embodiments, for example, the apparatuscomprising the one or more computers or equivalent devices may beoperable to map surface features of articles smaller than 500 nm, 250nm, 200 nm, 150 nm, 125 nm, 110 nm, 100 nm, 90 nm, 80 nm, 70 nm, 60 nm,50 nm, 40 nm, 30 nm, 20 nm, 10 nm, or 1 nm (10 Å) in their smallestdimension, or even smaller, such as surface features of articles smallerthan 9 Å, 8 Å, 7 Å, 6 Å, 5 Å, 4 Å, 3 Å, 2 Å, or 1 A in their smallestdimension. In view of the foregoing, the apparatus comprising the one ormore computers or equivalent devices may be operable to, in someembodiments, for example, map surface features of articles between 0.1nm and 1000 nm, such as between 0.1 nm and 500 nm, including between 0.1nm and 250 nm, and further including between 0.1 nm and 100 nm, and evenfurther including between 0.1 nm and 80 nm.

In view of the foregoing, the apparatus may be operable to detect and/ormap surface features of articles such as particle contaminationcomprising particles that are nanometer-sized (i.e., admits of nm unitsas measured) or smaller in their smallest dimension (e.g., length,width, or height). In some embodiments, for example, the apparatus maybe operable to detect and/or map surface and/or subsurface particlessmaller than 125 nm, such as smaller than 100 nm, including smaller than80 nm, and further including smaller than 10 nm in their smallestdimension. In some embodiments, for example, the apparatus may beoperable to map surface and/or subsurface particles smaller than 4 nm inheight.

Further in view of the foregoing, the apparatus may be operable todetect and/or map surface features of articles such as defectscomprising scratches (e.g., circumferential scratches) that aremicrometer-sized (i.e., admits of μm units as measured) or smaller, suchas nanometer-sized (i.e., admits of nm units as measured) or smaller,such as angstrom-sized (i.e., admits of A units as measured) or smaller,in their smallest dimension (e.g., length, width, or depth). Withrespect to micrometer-sized scratches, the apparatus may be operable todetect and/or map scratches from, for example, 1 μm to 1000 μm inlength, which may be significantly longer than the wavelength ofphotons/light emitted from a photon emitter of the apparatus. In someembodiments, for example, the apparatus may be operable to detect and/ormap surface features such as defects comprising scratches smaller than1000 μm, such as smaller than 500 μm, including smaller than 250 μm,further including smaller than 100 μm, and even further includingsmaller than 50 μm in scratch length. With respect to nanometer-sizedscratches, the apparatus may be operable to detect and/or map scratchesfrom, for example, 1 nm to 500 nm in scratch width. In some embodiments,for example, the apparatus may be operable to detect and/or map surfacefeatures such as defects comprising scratches smaller than 500 nm, suchas smaller than 250 nm, including smaller than 100 nm, further includingsmaller than 50 nm, and even further including smaller than 15 nm inscratch width. Surprisingly, due to a high level of spatial coherence,the apparatus may be operable to detect and/or map angstrom-sizedscratches with respect to scratch depth. In some embodiments, forexample, the apparatus may be operable to detect and/or map surfacefeatures such as defects comprising scratches smaller than 50 Å, such assmaller than 25 Å, including smaller than 10 Å, further includingsmaller than 5 Å, and even further including smaller than 1 Å (e.g., 0.5Å) in scratch depth. For example, the apparatus may be operable todetect and/or map surface features such as defects comprising scratchessmaller than 500 μm in length, smaller than 100 nm in width, and smallerthan 50 Å in depth.

The apparatus comprising the one or more computers or equivalent devicesmay be operable to accurately and/or precisely map the position of afeature on an article's surface. With respect to accuracy, the apparatuscomprising the one or more computers or equivalent devices may beoperable to map the position of a feature on an article's surface withina micrometer-sized (i.e., admits of μm units as measured) radius orbetter. In some embodiments, for example, the apparatus comprising theone or more computers or equivalent devices may be operable toaccurately map the position of a feature on an article's surface withina radius of 100 μm, 90 μm, 80 μm, 70 μm, 60 μm, 50 μm, 40 μm, 30 μm, 20μm, 10 μm, 9 μm, 8 μm, 7 μm, 6 μm, 5 μm, 4 μm, 3 μm, 2 μm, or 1 μm, orbetter. Combinations of the foregoing may also be used to describe theaccuracy with which the apparatus comprising the one or more computersor equivalent devices may map the position of a feature on an article'ssurface. In some embodiments, for example, the apparatus comprising theone or more computers or equivalent devices may be operable toaccurately map the position of a feature on an article's surface withina radius ranging from 1 μm to 100 μm, such as from 1 μm to 50 μm,including from 1 μm to 30 μm, and further including from 5 μm to 10 μm.

The apparatus comprising the one or more computers or equivalent devicesmay be operable to accurately and/or precisely map the position of afeature on an article's surface (e.g., FIGS. 6A (top) and 6B (top))along with the feature's photon scattering intensity distribution (e.g.,FIGS. 6A (bottom) and 6B (bottom)). Mathematical integration of such aphoton scattering intensity distribution provides the size (e.g.,volume) of the respective feature. As such, the apparatus describedherein may characterize surface features both qualitatively andquantitatively. With respect to qualitative characterization of surfacefeatures, qualitative characterization includes a determination ofsurface feature type (e.g., particle, stain, scratch, void, etc.). Withrespect to quantitative characterization of surface features,quantitative characterization includes a determination of surfacefeature position on the article and/or surface feature size.Quantitative characterization of surface features may further includethe total number of surface features per article, as well as the numberof each type of surface feature. Such characterization information maybe cataloged across a plurality of articles and be used to correctmanufacturing trends leading to surface and/or subsurface defects.

Depending upon factors that may include the type of article, the type ofsurface features, and the like, it may be desirable at times to increasethe number of photons (e.g., photon energy) emitted from a single photonemitter or a plurality of photon emitters to provide an increasedscattering signal for characterization (e.g., qualitative and/orquantitative) of surface features of articles. Such an increase inphoton energy may be with respect to unit time for increased photonpower or photon flux, or with respect to unit area for increased photonflux density. Alternately, or in addition, it may be desirable toincrease detection time of a single photon emitter or a plurality ofphoton emitters to detect more photons for accurately and/or preciselymapping surface features. Alternately to one or both of increasing thephoton energy or detection time, or in addition to increasing the photonenergy and detection time, it may be desirable at times to minimizebackground noise including stray light from one or more photon emitters,background light, and/or background fluorescent radiation.

The apparatus described herein may be configured to process or inspectarticles at a rate greater than or commensurate with the rate at whichthe articles or workpieces thereof are produced. In some embodiments,for example, the apparatus may be configured to process or inspectarticles at a rate of at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14,16, 18, or 20 article(s) per second, which rate may be commensurate withthe rate at which the articles or workpieces thereof are produced. Insome embodiments, for example, the apparatus may be configured toprocess or inspect articles at a rate of no more than 20, 18, 16, 14,12, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 article(s) per second, which ratemay be commensurate with the rate at which the articles or workpiecesthereof are produced. Combinations of the foregoing may also be used todescribe the rate at which the articles or workpieces thereof areprocessed or inspected by the apparatus. In some embodiments, forexample, the apparatus may be configured to process or inspect at least1 and no more than 20 articles per second (e.g., between 1 and 20articles per second), such as at least 1 and no more than 10 articlesper second (e.g., between 1 and 10 articles per second), including atleast 1 and no more than 5 articles per second (e.g., between 1 and 5articles per second). Processing or inspecting articles at rates greaterthan or commensurate with the rate at which the articles or workpiecesthereof are produced is a function of many features of the apparatusdescribed herein, including, but not limited to, photon emitters and/orarticles that need not be moved (e.g., for scanning) during processingor inspecting. For example, an article such as a hard disk of a harddisk drive need not be rotated during processing or inspecting. As such,the apparatus may be configured to hold an article stationary whileemitting photons onto the surface of the article.

While the apparatus may be configured to process or inspect articles arate greater than or commensurate with the rate at which the articles orworkpieces thereof are produced, the apparatus may operate at a slowerrate if needed. In some embodiments, for example, the apparatus may beconfigured to process or inspect articles at a rate less than onearticle per second. In such embodiments, for example, the apparatus maybe configured to process or inspect articles at a rate less than onearticle per 5, 10, 25, 50, 75, or 100, or more, second(s).

The apparatus described herein comprising a photon emitter, an opticalsetup, a photon detector array, and a mapping means may be fullyautomated and function in different modes, including, but not limitedto, an ultrafast mode, an ultrasensitive mode, and ultrasensitive plusmode. With respect to the ultrafast mode, the apparatus may operate atleast 200 times faster than an optical surface analyzer (e.g.,KLA-Tencor Candela CS10 or CS20), detect surface features such asdefects comprising embedded particles down to at least 100 nm, partiallydetect surface features such as defects comprising scratches (e.g.,nanometer-sized scratches), and provide measurements of roughness. Withrespect to the ultrasensitive mode, the apparatus may operate at least50 times faster than an optical surface analyzer, detect surfacefeatures such as defects comprising embedded particles down to at least30 nm, and provide measurements of roughness. With respect to theultrasensitive plus mode, the apparatus may operate at least 20 timesfaster than an optical surface analyzer, detect surface features such asdefects comprising embedded particles down to at least 30 nm, fullydetect surface features such as defects comprising scratches (e.g.,nano-scratches), and provide measurements of roughness.

As such, as provided herein, is an apparatus, comprising a photonemitter configured to emit photons onto a surface of an article, aphoton detector array comprising a plurality of photon detectorsconfigured to receive photons scattered from features in the surface ofthe article; and a mapping means for mapping the features in the surfaceof the article, wherein the apparatus is configured to characterize thefeatures in the surface of the article by analyzing the photons receivedat the plurality of photon detectors. In some embodiments, the apparatusis configured to hold the article in a stationary position whileemitting photons onto the surface of the article. In some embodiments,the apparatus further comprises a telecentric lens, wherein thetelecentric lens is coupled to the photon detector array. In someembodiments, the apparatus is operable to process articles at a ratefaster than one article every 100 seconds. In some embodiments, theapparatus is operable to map features smaller than 80 nm in theirsmallest dimension. In some embodiments, the apparatus is operable tomap features greater than 0.10 nm in their smallest dimension. In someembodiments, the mapping means is operable to map features with at leasta 10-μm accuracy with respect to location.

Also provided herein is an apparatus, comprising a photon emitterconfigured to emit photons onto a surface of an article, a photondetector array comprising a plurality of photon detectors configured toreceive photons scattered from features in the surface of the article;and a mapping means for mapping the features in the surface of thearticle, wherein the apparatus is operable to process articles at a ratefaster than one article every 100 seconds. In some embodiments, theapparatus is configured to hold the article in a stationary positionwhile emitting photons onto the surface of the article. In someembodiments, the apparatus further comprises a telecentric lens, whereinthe telecentric lens is coupled to the photon detector array. In someembodiments, the apparatus is operable to process articles at a ratefaster than one article per second. In some embodiments, the apparatusis operable to map features smaller than 80 nm in their smallestdimension. In some embodiments, the apparatus is operable to mapfeatures greater than 0.10 nm in their smallest dimension. In someembodiments, the mapping means is operable to map features down to atleast a 10-μm precision with respect to location.

Also provided is an apparatus, comprising a photon emitter configured toemit photons onto a surface of an article; a telecentric lens; a photondetector array comprising a plurality of photon detectors coupled to thelens configured to receive photons scattered from one or more featuresin the surface of the article; and a mapping means for mapping the oneor more features in the surface of the article, wherein the apparatus isoperable to map features smaller than 80 nm in their smallest dimension.In some embodiments, the apparatus is configured to hold the article ina stationary position while emitting photons onto the surface of thearticle. In some embodiments, the apparatus is operable to processarticles at a rate faster than one article every 100 seconds. In someembodiments, the apparatus is operable to process articles at a ratefaster than one article per second. In some embodiments, the apparatusis operable to map features smaller than 25 nm in their smallestdimension. In some embodiments, the apparatus is operable to mapfeatures greater than 0.10 nm in their smallest dimension. In someembodiments, the mapping means is operable to map features with at leasta 10-μm accuracy with respect to location.

Also provided is an apparatus, comprising a photon emitter configured toemit photons onto a surface of an article; a telecentric lens; a photondetector array coupled to the lens configured to receive photonsscattered from one or more features in the surface of the article; and amapping means for mapping the one or more features in the surface of thearticle, wherein the apparatus is operable to map features smaller than80 nm in their smallest dimension. In some embodiments, the apparatus isconfigured to hold the article in a stationary position while emittingphotons onto the surface of the article. In some embodiments, theapparatus is operable to process articles at a rate faster than onearticle every 100 seconds. In some embodiments, the apparatus isoperable to process articles at a rate faster than one article persecond. In some embodiments, the apparatus is operable to map featuressmaller than 25 nm in their smallest dimension. In some embodiments, theapparatus is operable to map features greater than 0.10 nm in theirsmallest dimension. In some embodiments, the mapping means is operableto map features down to at least a 10-μm precision with respect tolocation.

Also provided is an apparatus, comprising a photon emitting means foremitting photons onto a surface of an article, a photon detecting meansfor detecting photons scattered from features in the surface of thearticle; and a mapping means for mapping the features in the surface ofthe article, wherein the apparatus is operable to process articles at arate faster than one article every 100 seconds. In some embodiments, theapparatus is configured to hold the article in a stationary positionwhile emitting photons onto the surface of the article. In someembodiments, the article is greater than 500 square micrometers. In someembodiments, the apparatus is operable to process articles at a ratefaster than five article per second. In some embodiments, the apparatusis operable to map features smaller than 80 nm in their smallestdimension. In some embodiments, the mapping means is further foranalyzing scattering intensity distribution of photons scattered fromfeatures in the surface of the article.

Also provided is an apparatus, comprising a photon emitting means foremitting photons onto a surface of an article, a photon detecting meansfor detecting photons scattered from features in the surface of thearticle; and a mapping means for mapping the features in the surface ofthe article, wherein the mapping means is operable to map features downto at least a 10-μm precision with respect to location. In someembodiments, the apparatus is configured to hold the article in astationary position while emitting photons onto the surface of thearticle. In some embodiments, the apparatus is operable to processarticles at a rate faster than one article every 100 seconds. In someembodiments, the apparatus is operable to process articles at a ratefaster than one article per second. In some embodiments, the apparatusis operable to map features smaller than 80 nm in their smallestdimension. In some embodiments, the mapping means is further configuredto map scattering intensity distribution of photons scattered fromfeatures in the surface of the article.

Also provided herein is a device, comprising a feature mapper configuredto map features about a surface of an article from signals provided by aphoton detector array, wherein the signals correspond to photonsscattered from the features about the surface of the article, andwherein the feature mapper is configured for characterizing the featuresabout the surface of the article by analyzing the photons received atthe photon detector array. In some embodiments, the feature mapper isconfigured for qualitatively and/or quantitatively characterizing thefeatures about the surface of the article. In some embodiments,quantitatively characterizing the features about the surface of thearticle comprises determining the size and/or number of features aboutthe surface of the article. In some embodiments, the device is operableto map features smaller than 80 nm in their smallest dimension. In someembodiments, the device is operable to process articles at a rate fasterthan one article every 100 seconds.

While the invention has been described and/or illustrated by means ofparticular embodiments and/or examples, and while these embodimentsand/or examples have been described in considerable detail, it is notthe intention of the applicant(s) to restrict or in any way limit thescope of the invention to such detail. Additional adaptations and/ormodifications of the invention may readily appear to persons havingordinary skill in the art to which the invention pertains, and, in itsbroader aspects, the invention may encompass these adaptations and/ormodifications. Accordingly, departures may be made from the foregoingembodiments and/or examples without departing from the scope of theinvention, which scope is limited only by the following claims whenappropriately construed.

What is claimed is:
 1. An apparatus, comprising: a photon emitterconfigured to emit photons onto a surface of an article, a photondetector array comprising a plurality of photon detectors configured toreceive photons scattered from features in the surface of the article;and a mapping means for mapping the features in the surface of thearticle, wherein the apparatus is configured to characterize thefeatures in the surface of the article by analyzing the photons receivedat the plurality of photon detectors.
 2. The apparatus of claim 1,wherein the apparatus is configured to hold the article in a stationaryposition while emitting photons onto the surface of the article.
 3. Theapparatus of claim 1, further comprising a telecentric lens, wherein thetelecentric lens is coupled to the photon detector array.
 4. Theapparatus of claim 1, wherein the apparatus is operable to processarticles at a rate faster than one article per 10 seconds.
 5. Theapparatus of claim 1, wherein the apparatus is operable to map featuressmaller than 80 nm in their smallest dimension.
 6. The apparatus ofclaim 1, wherein the apparatus is operable to map features greater than0.10 nm in their smallest dimension.
 7. The apparatus of claim 1,wherein the mapping means is operable to map features with at least a10-μm accuracy with respect to location.
 8. An apparatus, comprising: aphoton emitter configured to emit photons onto a surface of an article;a telecentric lens; a photon detector array comprising a plurality ofphoton detectors coupled to the lens configured to receive photonsscattered from one or more features in the surface of the article; and amapping means for mapping the one or more features in the surface of thearticle, wherein the apparatus is operable to map features smaller than80 nm in their smallest dimension.
 9. The apparatus of claim 8, whereinthe apparatus is configured to hold the article in a stationary positionwhile emitting photons onto the surface of the article.
 10. Theapparatus of claim 8, wherein the apparatus is operable to processarticles at a rate faster than one article every 100 seconds.
 11. Theapparatus of claim 8, wherein the apparatus is operable to processarticles at a rate faster than one article per second.
 12. The apparatusof claim 8, wherein the apparatus is operable to map features smallerthan 25 nm in their smallest dimension.
 13. The apparatus of claim 8,wherein the apparatus is operable to map features greater than 0.10 nmin their smallest dimension.
 14. The apparatus of claim 8, wherein themapping means is operable to map features with at least a 10-μm accuracywith respect to location.
 15. An apparatus, comprising: a photonemitting means for emitting photons onto a surface of an article, aphoton detecting means for detecting photons scattered from features inthe surface of the article; and a mapping means for mapping the featuresin the surface of the article, wherein the apparatus is operable toprocess articles at a rate faster than one article every 100 seconds.16. The apparatus of claim 15, wherein the apparatus is configured tohold the article in a stationary position while emitting photons ontothe surface of the article.
 17. The apparatus of claim 15, wherein thearticle is greater than 500 square micrometers.
 18. The apparatus ofclaim 15, wherein the apparatus is operable to process articles at arate faster than five article per second.
 19. The apparatus of claim 15,wherein the apparatus is operable to map features smaller than 80 nm intheir smallest dimension.
 20. The apparatus of claim 15, wherein themapping means is further for analyzing scattering intensity distributionof photons scattered from features in the surface of the article.
 21. Adevice, comprising: a feature mapper configured to map features about asurface of an article from signals provided by a photon detector array,wherein the signals correspond to photons scattered from the featuresabout the surface of the article, and wherein the feature mapper isconfigured for characterizing the features about the surface of thearticle by analyzing the photons received at the photon detector array.22. The device of claim 21, wherein the feature mapper is configured forqualitatively and/or quantitatively characterizing the features aboutthe surface of the article.
 23. The device of claim 22, whereinquantitatively characterizing the features about the surface of thearticle comprises determining the size and/or number of features aboutthe surface of the article.
 24. The device of claim 21, wherein thedevice is operable to map features smaller than 80 nm in their smallestdimension.
 25. The device of claim 21, wherein the device is operable toprocess articles at a rate faster than one article every 100 seconds.